[DOC] Consistent naming for Functions vs Methods

[BenKurrek]

Is your feature request related to a problem? Please describe.
Currently, there is not a consistent naming scheme for 'methods' and 'functions'. We should either name them all 'methods' or all 'functions'

Describe the solution you'd like
As per this discussion, we should name everything as methods.

[frol]

I want to bring to attention that the transaction action related to function/method call is called "FunctionCall", the view function/method is called "CallFunction" (consistency, is not our strongest point...), the access key kind is called "FunctionCall"

[bucanero]

After additional discussion on Zulip, we'll stick to function (See #905 )